Statement Of Financial Position [Abstract]
| Concept |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-01-01 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-01-01 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | |||||||||||||||||
| Assets [abstract] | |||||||||||||||||
| Non-current assets [abstract] | |||||||||||||||||
| Property, plant and equipment |
135,400,000
GBP
|
— | — | — | — | — |
130,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Investment property |
2,153,000,000
GBP
|
— | — | — | — | — |
2,032,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Investments accounted for using equity method |
4,900,000
GBP
|
— | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Deferred tax assets |
2,600,000
GBP
|
— | — | — | — | — |
7,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Non-current assets |
2,308,800,000
GBP
|
— | — | — | — | — |
2,181,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current assets [abstract] | |||||||||||||||||
| Cash and cash equivalents |
167,400,000
GBP
|
— | — | — | — |
235,700,000
GBP
|
235,700,000
GBP
|
— | — | — | — |
259,400,000
GBP
|
— | — | — | — | — |
| Non-current assets or disposal groups classified as held for sale or as held for distribution to owners |
44,200,000
GBP
|
— | — | — | — | — |
21,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current assets |
229,700,000
GBP
|
— | — | — | — | — |
279,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Assets |
2,538,500,000
GBP
|
— | — | — | — | — |
2,461,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | |||||||||||||||||
| Equity [abstract] | |||||||||||||||||
| Issued capital |
11,000,000
GBP
|
— | — | — |
11,000,000
GBP
|
— |
11,000,000
GBP
|
— |
11,000,000
GBP
|
— | — | — | — | — | — | — |
11,000,000
GBP
|
| Retained earnings |
1,147,900,000
GBP
|
1,147,900,000
GBP
|
— | — | — | — |
1,059,200,000
GBP
|
1,059,200,000
GBP
|
— | — | — | — |
1,011,900,000
GBP
|
— | — | — | — |
| Share premium |
83,100,000
GBP
|
— | — |
83,100,000
GBP
|
— | — |
83,100,000
GBP
|
— | — | — |
83,100,000
GBP
|
— | — | — | — |
83,100,000
GBP
|
— |
| Other reserves |
88,700,000
GBP
|
— |
88,700,000
GBP
|
— | — | — |
117,300,000
GBP
|
— | — |
117,300,000
GBP
|
— | — | — |
96,400,000
GBP
|
— | — | — |
| Equity |
1,330,700,000
GBP
|
— | — | — | — | — |
1,270,600,000
GBP
|
— | — | — | — | — | — | — |
1,202,400,000
GBP
|
— | — |
| Liabilities [abstract] | |||||||||||||||||
| Non-current liabilities [abstract] | |||||||||||||||||
| Deferred tax liabilities |
109,900,000
GBP
|
— | — | — | — | — |
159,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Non-current liabilities |
975,900,000
GBP
|
— | — | — | — | — |
1,032,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | |||||||||||||||||
| Current tax liabilities, current |
4,500,000
GBP
|
— | — | — | — | — |
300,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current liabilities |
231,900,000
GBP
|
— | — | — | — | — |
158,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Liabilities |
1,207,800,000
GBP
|
— | — | — | — | — |
1,190,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — |